[Resolved] return to last used language after redirect from SSO provider

I have an idea of hooking into where the cookie is updated, and using the original value to do the redirect, but I can't seem to get it to work. In the same place I'm getting the language cookie back as 'en', if I add the following:

add_action('wpml_language_has_switched', array( $this, 'get_cookie_lang' ), 0, 3 );

and add the function get_cookie_lang() to the class:

	public function get_cookie_lang($code, $cookie_lang, $original_language) {
		echo "\$code = $code<br>\$cookie_lang = $cookie_lang<br>\$original_language = $original_language<br>";
	}

it does not output anything, which leads me to believe the hook hasn't fired by then, but then how has the cookie lang already been changed?

I have found a workaround by using the wpml_before_init hook to grab the original language cookie before wpml resets it.

If that is not recommended, please advise, if it should be fine, the thread can be closed.

What I'm doing is developing a plugin to integrate a state-run SSO service (Iceland) - which will guarantee the identity of logged-in users.
I'm developing it first and foremost for a non-profit I volunteer for, but would like to release it as well as I know others are looking for the same functionality.
I want it to support sites running WPML properly (the non-profit site uses it, so I need to do it anyway). The SSO service only allows you to provide one url for it to send the user along with a SAML2.0 token to, so on that page I need to process the SAML2.0 token, and then send the user back to the same language of the site they were on before redirecting the the SSO login page.

Example:
User is on hidden link - clicks on the login link, which takes it to the login page of the SSO service. The SSO service sends the user back to hidden link, where the token is processed and verified, then the user is sent to their account page on the same language they were on previously (IS) -> hidden link (instead of the EN version -> hidden link )